From db0beb72c7a444d0c252b8294907c398ba96da77 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Tue, 24 Sep 2013 21:26:21 +0300
Subject: drm/i915: Don't underflow bestppm
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We do 'bestppm - 10' in vlv_find_best_dpll() but never check whether
that might underflow. Add such a check.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit c686122c638838ce7113aeb22e4f1c50446de6eb)
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 5b95e2a42caa..60aa0121d7b8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -708,7 +708,7 @@ vlv_find_best_dpll(const intel_limit_t *limit, struct drm_crtc *crtc,
 						bestppm = 0;
 						flag = 1;
 					}
-					if (ppm < bestppm - 10) {
+					if (bestppm >= 10 && ppm < bestppm - 10) {
 						bestppm = ppm;
 						flag = 1;
 					}
-- 
1.8.5.rc3